The present invention relates in generally to a focal plane array, and more particularly, to a multi-band focal plane array (FPA) architecture.
The military has multiple needs for day and night surveillance and reconnaissance. The ultimate goal of an optical imaging sensor is to achieve a high probability of detection of a target while simultaneously maintaining an acceptably low false alarm rate. As a target has a spectral reflectivity or emissivity that varies from the background or from clutter, it is often desirable to detect light from the target in two or more wavebands. Thereby, the target can be detected using the response in the two or three wavebands compared to the response of the focal plane array to the background or clutter in these wavebands. It is also desirable for performing target discrimination in one focal plane array instead of using separate focal plane arrays at elevated temperature.
Research has thus been intensely performed to realize a single focal plane array operative to detect a target over multiple spectral ranges. Currently, simultaneous multi-band detection for a single focal plane array is still limited within the infrared range, that is, many of the currently available detectors are only operative to perform simultaneous detection at long-wavelength infrared (LWIR), medium-wavelength infrared (MWIR), and short-wavelength infrared (SWIR) bands. In addition, many of these detectors are only operable while being cryogenically cooled.